A presence system is a system that manages the current status of presentities, such as people and objects, i.e., presence information. With a presence system, if the presence information of any presentity is updated, then watchers that have subscribed to the presence information of that presentity are notified of that presence information in real time.
In recent years, RFID technology, which can send and receive information without human intervention, has been coming into use in product management systems, such as distribution systems and inventory management systems. In conventional product management systems, information management is carried out in a proprietary fashion. However, it is expected that the presence systems would more and more applied to the product management. This is because presence system can manage current status of the product (or article) and notify updated information in real time.
Every time presence information is updated in a conventional presence system, the watcher is notified of that updated presence information. However, when trying to adapt a presence system to the management of product, the number of notifications of presence information increases enormously. Consequently, it is difficult for a watcher to efficiently manage presence information. For example, to efficiently manage products, a watcher must classify the presence information of the products by itself. In addition, the watcher must subscribe to the presence information of each of lots of products one by one. Consequently, there is a problem in that the burden on the watcher adversely increases.
Furthermore, there is a problem in that, if a watcher is notified of presence every time the presence information of lots of products updates, then the frequency of the notifications increases and the volume of information transmitted increases considerably, which increases the load on the network.
JP 2004-72485A discloses the technology of a presence notifying method, wherein all presence information is merged and transmitted every fixed time period if the presence information should be notified to the watcher.